Extinction Level Event
It seems as though we are very possibly very fucked. Note-- this is an update on the similar scenario I posted last June. For various reasons, this seems more plausible than before, with the most frightening part being the three terrible indications from data in the Gulf that suggest an imminent disaster-- "...the appearance of large fissures or rifts splitting open the ocean floor, a rise in the elevation of the seabed, and the massive venting of methane and other gases into the surrounding water."
The bottom line: BP’s Deepwater Horizon drilling operation may have triggered an irreversible, cascading geological Apocalypse that will culminate with the first mass extinction of life on Earth in many millions of years.
The oil giant drilled down miles into a geologically unstable region and may have set the stage for the eventual premature release of a methane mega-bubble.
Ryskin’s methane extinction theory
Northwestern University's Gregory Ryskin, a bio-chemical engineer, has a theory: The oceans periodically produce massive eruptions of explosive methane gas. He has documented the scientific evidence that such an event was directly responsible for the mass extinctions that occurred 55 million years ago. 
Many geologists concur: "The consequences of a methane-driven oceanic eruption for marine and terrestrial life are likely to be catastrophic. Figuratively speaking, the erupting region "boils over," ejecting a large amount of methane and other gases (e.g., CO2, H2S) into the atmosphere, and flooding large areas of land. Whereas pure methane is lighter than air, methane loaded with water droplets is much heavier, and thus spreads over the land, mixing with air in the process (and losing water as rain). The air-methane mixture is explosive at methane concentrations between 5% and 15%; as such mixtures form in different locations near the ground and are ignited by lightning, explosions and conflagrations destroy most of the terrestrial life, and also produce great amounts of smoke and of carbon dioxide..." 
The warning signs of an impending planetary catastrophe—of such great magnitude that the human mind has difficulty grasping it-would be the appearance of large fissures or rifts splitting open the ocean floor, a rise in the elevation of the seabed, and the massive venting of methane and other gases into the surrounding water.
Such occurrences can lead to the rupture of the methane bubble containment—it can then permit the methane to breach the subterranean depths and undergo an explosive decompression as it catapults into the Gulf waters. 
All three warning signs are documented to be occurring in the Gulf.